A wavelength division multiplexing (Wavelength Division Multiplex, hereinafter referred to as WDM) optical network can perform, in an optical domain, multiplexing, transmission, amplification, routing, recovery and so on of a signal, and has become a focus in research of the optical communication field. According to whether a WDM optical network node performs electrical processing on an optical signal, optical networks may be classified into two types: transparent (Transparent) network and opaque (Opaque) network. For a transparent optical network, a signal is in a form of an optical signal all along a transporting process from a source node to a sink node, and regeneration, switching and wavelength transformation of the signal are completed in the optical domain. Because a node does not have a regeneration capability of an electrical signal, the transparent optical network is essentially an analog transport network. Therefore, signal impairment and various harmful physical effects such as crosstalk, non-linearity, and dispersion cannot be eliminated in the transporting process. Accumulation of noise is continuous and analog, and quality of the signal which finally reaches the sink node is related to the noise introduced in the entire transporting process. Moreover, some physical impairment not only influences wavelength performance of a local channel, but may also impose impact on wavelength performance of another channel. Therefore, when an optical path connection is established in the WDM optical network, it is very meaningful to fully consider the physical effects that have negative influence on the quality of the signal, such as the physical impairment.
In the prior art, a simple principle is generally adopted to avoid the foregoing problem, that is, performing wavelength assignment from two sides to the middle in a scenario of mixed-rate transmission of 10 G/40 G services. For example, for a wavelength division network of a 40-wave system, assignment starts from λ1 for a 10 G service, while assignment starts from λ40 for a 40 G service. In other scenarios, there is still no better method to solve the problem.
However, the prior art has at least the following disadvantages: The mutual influence of service performance between different wavelengths is not fully considered, so that during expansion of a newly established service, a bit error or even service interruption occurs in a channel with an activated service.